1. Field of the Invention
The present invention relates generally to robotic gripper mechanisms.
2. Background of the Invention
Typical robotic grippers (also known as end effectors) for automated data storage libraries are slow-speed electric pinching mechanisms for gripping onto a standard sized box-shaped modia cassette. The size of the data cassette usually dictates the range of movement of the gripper jaws. The simplest solution for proper movement of the jaws is to hinge them in the rear and provide an actuator to push them apart and pull them together in order to grip an object. Typically, a motor is used to drive a nut and linkage arrangement that moves the gripper fingers (jaws) together or apart. This typical gripper design has several limitations related to the variability of cassette size.
The first limitation is the finger of the gripper. Because of their pivot point, the jaws will not remain parallel to each other as the cassette size varies in its tolerance range, and certainly will not remain parallel for a non-standard or smaller form factor cassette. Parallelism is desirable to control the attitude and gripping surface friction of the jaws.
A second limitation of the prior art gripper design relates to the linkage arms that drive the jaws in a non-linear force relationship. As the finger pivot angle changes, the linkage angles change, and a small change in gripper pinch width could result in a large difference in pinch force applied to the cassette.
Therefore, it would be desirable to have a robot gripper that can grip onto several different shaped objects with consistent orientation in space to keep the objects aligned with the library structure, while retaining constant grip force.
The present invention provides a robotic gripper mechanism. The invention comprises gripping jaws and a wedge that moves along angled groove between the gripping jaws. The angled grooves are connected to the gripping jaws, and the wedge moves the gripping jaws together and apart as it slides backward and forward along the angled grooves. The wedge also keeps the gripper jaws parallel to each other as they open and close. A motor moves the wedge backward and forward, and guiding surfaces attached to the base prevent the jaws from moving horizontally relative to the base.